The first two steps are usually referred to as the fetch phase and the step 3 is known as the execution phase. Fetch cycle basically involves read the next instruction from the memory into the CPU and along with that update the  contents of the program counter. In the execution phase, it interpretes the opcode and perform the indicated operation. The instruction fetch and execution phase together known as instruction cycle. The basic instruction cycle is shown in the Figure 5.3.
                                      
                                                         Figure 5.3: Basic Instruction cycle

In cases, where an instruction occupies more than one word, step 1 and step 2 can be repeated as many times as necessary to fetch the complete instruction. In these cases, the execution of a instruction may involve one or more operands in memory, each of which requires a memory access. Further, if indirect addressing is used, then additional memory access are required.